1. Field of the Invention
The present invention relates to an AlxGayIn1-x-yN (0<x≦1, 0≦y≦1, x+y≦1) substrate and a cleaning method of the AlxGayIn1-x-yN (0<x≦1, 0≦y≦1, x+y≦1) substrate. The present invention also relates to an AlN substrate with which an epitaxial film of low haze level can stably be grown, and a cleaning method of the AlN substrate. In this specification, AlxGayIn1-x-yN (0<x≦1, 0≦y≦1, x+y≦1) is abbreviated as AlxGayIn1-x-yN.
2. Description of the Background Art
An AlxGayIn1-x-yN substrate can be suitably used as a substrate for various semiconductor devices such as optical devices and/or electronic devices.
A representative growth method of an AlxGayIn1-x-yN crystal is HVPE (Hydride Vapor Phase Epitaxy) method, and an AlxGayIn1-x-yN substrate can be manufactured from the AlxGayIn1-x-yN crystal. By growing various epitaxial films on the surface of AlxGayIn1-x-yN substrate, semiconductor devices such as optical devices and/or electronic devices can be obtained.
Among AlxGayIn1-x-yN substrates, an AlN substrate has an energy bandgap of 6.2 eV, a thermal conductivity of about 3.3 WK−1cm−1 and high electric resistance, and therefore it is receiving attention as a substrate for various semiconductor devices such as optical devices and/or electronic devices.
The AlN substrate can be manufactured from an AlN crystal grown through HVPE method or sublimation method. By growing various epitaxial films on the surface of the AlN substrate, semiconductor devices such as optical devices and/or electronic devices can be obtained.
For example, a light emitting diode obtained by growing an AlGaN film and the like on an AlN substrate is disclosed in Toshio Nishida et al., “GaN-free transparent ultraviolet light-emitting diodes”, 2003, Appl. Phys. Lett., vol. 82, No. 1. Additionally, a light emitting diode formed on a bulk AlN substrate is disclosed in Toshio Nishida et al., “The Characteristics of UV-LED Grown on Bulk AlN Substrate Under Large Current Injection”, the 51st spring meeting of the Japan Society of Applied Physics and Related Societies, extended abstracts, March 2004, p. 409.